Voltage measurement system

Abstract

A voltage measurement system includes: a first reference signal transmission device (communication device) including a first master oscillator that generates a first master clock signal and a first reference signal generation circuit that generates a first reference signal based on the first master clock signal; and a first voltage measurement device including a first slave oscillator, a first correction circuit that corrects an oscillation frequency of the first slave oscillator based on the first reference signal, and a first voltage measurement circuit. The voltage measurement system includes: a normal mode; and a correction mode in which the first reference signal is transmitted from the first reference signal transmission device (communication device) to the first voltage measurement device, and the oscillation frequency of the first slave oscillator is synchronized with an oscillation frequency of the first master oscillator using the first reference signal.

1 . A voltage measurement system that measures a voltage of a battery cell, the voltage measurement system comprising:
 a first reference signal transmission device including a first master oscillator that generates a first master clock signal and a first reference signal generation circuit that generates a first reference signal based on the first master clock signal; and   a first voltage measurement device including a first slave oscillator that generates a first clock signal, a first correction circuit that corrects an oscillation frequency of the first slave oscillator based on the first reference signal, a first voltage measurement circuit, and a first measurement control circuit that controls the first voltage measurement circuit based on the first clock signal, wherein   the voltage measurement system includes:
 a normal mode in which a command signal is transmitted and received between the first reference signal transmission device and the first voltage measurement device; and 
 a correction mode in which the first reference signal is transmitted from the first reference signal transmission device to the first voltage measurement device, and the oscillation frequency of the first slave oscillator is synchronized with an oscillation frequency of the first master oscillator using the first reference signal. 
   
     
     
         2 . The voltage measurement system according to  claim 1 , wherein
 the first reference signal transmission device further includes:
 a communication circuit that transmits and receives the command signal; and 
 a multiplexer that transmits and receives the command signal and the first reference signal, and 
   the multiplexer transmits and receives the command signal in the normal mode and transmits and receives the first reference signal in the correction mode.   
     
     
         3 . The voltage measurement system according to  claim 1 , wherein
 the first voltage measurement device further includes:
 a first communication circuit that transmits and receives the command signal; and 
 a first multiplexer that transmits and receives the command signal and the first reference signal, and 
   the first multiplexer transmits and receives the command signal in the normal mode and transmits and receives the first reference signal in the correction mode.   
     
     
         4 . The voltage measurement system according to  claim 3 , wherein
 the first voltage measurement device further includes a first selection circuit that transmits and receives the command signal and the first reference signal, and   the first selection circuit transmits and receives the command signal to and from the first communication circuit in the normal mode, and receives the first reference signal and transmits the first reference signal to the first correction circuit and the first multiplexer in the correction mode.   
     
     
         5 . The voltage measurement system according to  claim 3 , wherein
 the first multiplexer transmits the first reference signal to an other element in the voltage measurement system in the correction mode.   
     
     
         6 . The voltage measurement system according to  claim 1 , wherein
 the first measurement control circuit causes the first voltage measurement circuit to measure voltage in a cycle determined based on the first clock signal.   
     
     
         7 . The voltage measurement system according to  claim 1 , wherein
 the first correction circuit counts a total number of pulse signals included in the first reference signal and corrects the oscillation frequency of the first slave oscillator based on the total number.   
     
     
         8 . The voltage measurement system according to  claim 7 , wherein
 the first correction circuit corrects the oscillation frequency of the first slave oscillator based on a correction difference value calculated from (i) a total number of clocks of the first master oscillator corresponding to the total number of the pulse signals and (ii) a total number of clocks of the first slave oscillator in a period corresponding to the first reference signal.   
     
     
         9 . The voltage measurement system according to  claim 7 , wherein
 the first correction circuit skips correction of the oscillation frequency of the first slave oscillator when the total number counted is not in a predetermined range.   
     
     
         10 . The voltage measurement system according to  claim 1 , wherein
 the first voltage measurement device further includes:
 a first low-speed oscillator that oscillates at a lower oscillation frequency than the first slave oscillator; and 
 a first low-speed correction circuit that corrects the oscillation frequency of the first low-speed oscillator based on the first clock signal from the first slave oscillator. 
   
     
     
         11 . The voltage measurement system according to  claim 10 , wherein
 the first low-speed correction circuit corrects the oscillation frequency of the first low-speed oscillator based on the first clock signal from the first slave oscillator corrected based on the first reference signal.   
     
     
         12 . The voltage measurement system according to  claim 1 , further comprising:
 a second voltage measurement device that receives the first reference signal via the first voltage measurement device, wherein   the second voltage measurement device includes:
 a second slave oscillator that generates a second clock signal; 
 a second correction circuit that corrects an oscillation frequency of the second slave oscillator based on the first reference signal; 
 a second voltage measurement circuit; and 
 a second measurement control circuit that controls the second voltage measurement circuit based on the second clock signal. 
   
     
     
         13 . The voltage measurement system according to  claim 1 , wherein
 the first reference signal transmission device further includes:
 a voltage measurement circuit; and 
 a measurement control circuit that controls the voltage measurement circuit based on the first master clock signal. 
   
     
     
         14 . The voltage measurement system according to  claim 1 , further comprising:
 a high-precision oscillator that generates a high-precision clock signal that is more precise than the first master oscillator, wherein   the first reference signal transmission device further includes a first master correction circuit that corrects the oscillation frequency of the first master oscillator based on the high-precision clock signal.   
     
     
         15 . The voltage measurement system according to  claim 1 , further comprising:
 a second reference signal transmission device including a second master oscillator that generates a second master clock signal and a second reference signal generation circuit that generates a second reference signal based on the second master clock signal, wherein   each of the first reference signal transmission device and the second reference signal transmission device receives a control clock signal that is a clock signal input from outside,   the first reference signal transmission device further includes a first master correction circuit that corrects the oscillation frequency of the first master oscillator based on the control clock signal, and   the second reference signal transmission device further includes a second master correction circuit that corrects an oscillation frequency of the second master oscillator based on the control clock signal.   
     
     
         16 . The voltage measurement system according to  claim 1 , further comprising:
 a second reference signal transmission device including a second master oscillator that generates a second master clock signal and a second reference signal generation circuit that generates a second reference signal based on the second master clock signal, wherein   the second reference signal transmission device further includes a second master correction circuit that corrects an oscillation frequency of the second master oscillator based on the first master clock signal.